Burst communications messages are characterized by short length message transmissions conveying a predetermined amount of data. A uni-directional data link for implementing burst communications is well known in the art. A bi-directional burst communications data link between a plurality of users, however, has historically been too complex to implement in a practical and cost effective manner because such a data link requires precise timing between the plurality of users transmitting data messages and message acknowledgements. The timing problems are magnified as the number of users requesting access to the data link increases. Without sufficient timing synchronization and safeguards in the communications protocol, it is difficult to avoid simultaneous burst message transmission by multiple users resulting in signal interference on the data link and user confusion due to lost or uncompleted message transmissions. Accordingly, there is a need for a communications protocol to manage and control user access to a data link for bi-directional burst communications.